This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book provides a systematic overview of the properties, constraints, and technological issues of the high-dielectric constant (high-k) gate dielectric materials. High-k gate dielectric integration will be the indispensable key technology for sustaining further Complementary metal-oxide-semiconductor (CMOS) device downsizing to the nanoscale range, as sub-nanometer equivalent oxide thickness gate dielectric films can only be achieved with the use of high-k materials. Incorporation of the high-k materials into the present CMOS technology would require some major changes in the fabrication technique and the process sequence. Significant improvements in dealing with device instabilities have also been obtained by filling the oxygen vacancies with nitrogen and aluminum atoms, and by using complex forms of high-k oxides or silicates.